sched/assert: Store table for all registers instead of buffer

This way the registers can be read easily

sched/misc/assert.c

@@ -70,7 +70,7 @@
  * Private Data
  ****************************************************************************/
 
-static uint8_t g_last_regs[XCPTCONTEXT_SIZE] aligned_data(16);
+static uintptr_t g_last_regs[XCPTCONTEXT_REGS] aligned_data(16);
 
 #ifdef CONFIG_BOARD_COREDUMP
 static struct lib_syslogstream_s  g_syslogstream;